Glass for manufacture of glass-coated microwire

ABSTRACT

Glass for manufacturing by the casting technique glass-coated, continuous filament microwire from metals and alloys having a melting point above 1,450* C., for example, from nickel, palladium, nichrome, etc., which contains, apart from SiO2, B2O3, BaO, K2O and Li2O, also P2O5 present to the extent of 0.5-0.7 percent by weight of all the glass components.

United States Patent Serafima Petrovna Obidina Gogolevsky bulvar, 25, kv. 13; Alexandra Nikolaevna Bush, Zelenograd, Korpus 352, kv. 51, both of Moscow, U.S.S.R.

Appl. No. 857,578

Filed Sept. 12, 1969 Patented Oct. 26, 1971 Inventors GLASS FOR MANUFACTURE OF GLASS-COATED MICROWIRE 1 Claim, No Drawings [1.8. CI 106/54, 72/42, 106/48, 117/231, 161/196 Int. Cl C03c 3/08, C32b 3/08 Field of Search 72/42;

106/54, 50,48; 117/129, 231; l6l/l96 Taylor A Method of Drawing Metallic Filaments" Phys. Rev. 23 (1924) pp. 655- 660 QCl p4 Primary Examiner-Helen M. McCarthy Attorney-Waters, Roditi, Schwartz &,Nissen ABSTRACT: Glass for manufacturing by the casting technique glass-coated, continuous filament microwire from metals and alloys having a melting point above 1,450C., for example, from nickel, palladium, nichrome, etc., which contains, apart from SiO B 0 BaO, K 0 and L1 0, also P 0 present to the extent of 0.5-0.7 percent by weight of all the glass components.

GLASS FOR MANUFACTURE OF GLASS-COATED MICROWIRE This invention relates to glass intended for the manufacture of glass-coated microwire by the casting technique.

There is known a glass for the manufacture of glass-coated microwire by the casting technique, the composition of this known glass being as follows, weight percent:

SiO 75-79 BaO 1.5-2.5

(cf, The USSR Authors Certificate No. 186,660, cl. 32b, 3/08) The glass having the aforespecified composition is suitable exclusively for the manufacture of glass-coated microwire from metals whose melting point lies in the 1,350-1,450 C. range, e.g., nichrome, and is inapplicable where it is desired to manufacture microwire from metals having a melting point "above 1,450 C., e.g., nickel, palladium, cobalt-base alloys,

etc.

Moreover, the employment of the known glass for the manufacture of nichrome microwires does not make it possible to obtain a continuous thread, the wire length being generally not greater than l m.

It is an object of the present invention to eliminate the aforementioned disadvantages.

It is a further and more specific object of the present invention to provide a glass which will make it possible to manufacture glass-coated, continuous filament microwire from metals and alloys having a melting point above 1,450 C., e.g., from nickel, nichrome, palladium, cobalt-base alloys, etc., by the casting technique.

These objects have been accomplished by the provision of glass for the manufacture of glass-coated microwire having the following composition, weight percent:

SiO 79.0-83.0

BaO 1.5-2.5

The present invention is illustrated hereinbelow by the description of an exemplary procedure for producing glass to be used for the manufacture of glass-coated microwire.

The glass was melted in a gas-fired and electrically heated batch furnace, the composition of the charge being as follows (weight percent per ton of glass melt):

quartz sand 68.5

boric acid 25.3

15.2 2.0 1.2 0.5 P 0 0.6 The glass of the present invention is characterized by the following physical and chemical properties:

Coefficient of linear thermal expansion on the 20300aL C. range 260x10" l/deg. Softening point 660 C. Thermal stability 300 C. Temperature at which volume resistivity equals 10 Mohrn 400 C. Temperature at which glass viscosity equals 10 poises l,500 C. Chemical stability Class 1 of hydrolytic stability Upper crystallization limit 1,450" C.

Glass tubes are closed at one end and charged with a small quantity of a metal, such as nickel (m.p. l,450 C.), whereupon the tubes are placed in an induction furnace. High frequency currents cause the nickel charge to melt and heat the glass until its viscosity equals 10 -10 poises, so that a glass capillary can be readily drawn.

Incorporation of P 0 into the composition of the present glass provides for good wettability of the glass with the metal and results in filling the capillary being drawn with the molten metal and forming a microwire which is continuously wound onto a rotating spool.

1n the course of being drawn, the microwire is passed through a crystallizer which makes for microwire diameter constancy.

We claim:

1. Glass for the manufacture of glass-coated microwire which has the following analysis, weight percent:

BaO 1.5-2.5

Li O 0.3-0.7 

